1. Field of Invention
This invention relates to systems and methods of delivering anesthesia to tissue. Specifically, the invention relates to systems and methods of providing anesthesia to tissue using a catheter and introducer needle assembly, and applying a current to the needle assembly to create stimulation in the tissue to identify a target needle depth at which to deliver the anesthesia. The present application
2. Description of the Related Art
In certain instances, it is desirable to provide anesthesia at a point in a patient's tissue proximate to a nerve. Such procedures are known as peripheral block procedures. Typically, the clinician employs a hollow needle that is coated with an electrical insulator, leaving only the tip of the needle exposed. The clinician first locates anatomical landmarks to establish the location of the nerve. As the needle is inserted into the tissue, a small electric current is passed through the needle. The current passes to the patient's tissue at the tip of the needle (the only exposed portion of the needle) and causes surrounding muscle tissue to contract or “twitch.” This twitching is observed by the clinician and helps locate the needle tip. As the needle tip proceeds closer to the nerve, the clinician reduces the current and moves the needle tip to a point that is believed to be appropriately close to the nerve to be effective.
Once the needle tip is in place, the clinician delivers a bolus of anesthesia through the needle to the region around the nerve. Typically, such a delivery of anesthesia will deaden both the motor and sensory impulses. After delivery of the anesthesia, the rigid needle is withdrawn. Consequently, if more anesthesia is required, another needle must be inserted. Alternatively, some practitioners will insert a catheter through the needle so that the tip of the catheter is near the tip of the needle. The needle is then withdrawn over the catheter and the catheter remains in place. After the needle is threaded off the catheter, a special connector is attached to the catheter end to permit that delivery of additional anesthesia. This can be a time consuming process.